Technical Field
The present invention relates to a forming die assembly including dies that may be used for producing microcomponents such as microgears. In the dies, a raw material with a metal powder and a binder having plasticity is compacted into a green compact with a shape similar to that of the microcomponent.
Background Art
Recently, in the production of digital home appliances, advanced medical equipment, and IT devices, there are trends toward decreasing dimensions and increasing performances of the devices. Therefore, requirements for decreasing dimensions and wall thicknesses have been increasing for components of such devices. In view of this, although microcomponents basically have small dimensions and thin walls, the microcomponents are also required to be even smaller and have thinner walls. A production method for such microcomponents is disclosed in Japanese Patent Application of Laid-Open No. 2006-344581. In this method, a raw material with a metal powder and a binder having plasticity is filled in a die and is compressed by a punch, whereby a green compact with a shape similar to that of the target shape is formed. Then, the green compact is sintered.
According to the production method of the green compact disclosed in Japanese Patent Application of Laid-Open No. 2006-344581, the raw material is sufficiently filled at a portion of the die, which corresponds to a thin-walled portion of the target shape. Therefore, a green compact with high accuracy is obtained. In this case, since the raw material is different from a raw powder, which is used in an ordinary powder metallurgy process, and has plasticity, the raw material is difficult to use. That is, a predetermined amount of the raw material must be directly filled in the die, and this increases the steps in the process. The raw material is filled in the die at each compacting as is the case in an ordinary die forming for compacting a powder. However, in a case of forming a microcomponent, since the amount of raw material required for one compacting is extremely small, this production method is not efficient.